Can't add first dwarf scroll to the library

I have found all 4 dwarf scrolls. I added 2, 3, and 4 to the library but didn't add #1 early on (it never said "you can donate this to the museum"). Now when I try to donate it to the museum, I can't. But without doing so I can't understand the dwarf in the mines. Any suggestions? Thanks, all.

 

Hmm, maybe try and find another #1 dwarf scroll..
Maybe it's a bug or something?
Got the #1 pretty fast.. the #4 took me a eternity to get.. ._.

Hope someone can give you a better answer than me..

 

I'm already at level 95 in the mines and have only found one of each type of scroll. Maybe I need to try some of the early levels for another one?

 

Green slimes (mines and secret woods) drop it sometimes or you can hoe (bomb) the soil in the mines..
thats how I got mine.
But I don't remember what Level..
killing some Duggys could be another chance.. they drop it, too..
Maybe try the first 40 floors again.